1. Field of the Invention
The present invention relates to a semiconductor device, an electronic device, and a method of producing a semiconductor device, the devices being suitable for use in a structure including a semiconductor layer made of an organic material.
2. Description of the Related Art
Thin-film transistors (TFTs) are widely used as pixel transistors in electronic circuits, in particular, in active-matrix-driven flat display units. Recently, the use of an organic material as a semiconductor layer used for such a semiconductor device having a small thickness has attracted attention. In thin-film transistors including a semiconductor layer made of an organic material, i.e., organic thin-film transistors (OTFTs), the semiconductor layer can be deposited at a temperature lower than that in a structure including a semiconductor layer made of an inorganic material. Therefore, such organic thin-film transistors are advantageous in that thin-film transistors having a large area can be produced, and the organic thin-film transistors can be formed on a flexible substrate having poor heat resistance, e.g., a plastic substrate. Organic thin-film transistors are promising from the standpoint of realization of multifunctional devices and a reduction in cost.
Furthermore, in organic thin-film transistors, not only the semiconductor layer but also a gate insulating film, source-drain electrodes, and a gate electrode can be formed by a printing method or an evaporation method, and thus, the production cost can be further reduced. In general, the thicknesses of wirings for such source-drain electrodes and a gate electrode are in the range of 50 to 200 nm (refer to Christos D. Dimitrakopoulos and Patrick R. L. Malenfant, “Organic Thin-Film Transistors for Large Area Electronics”, “Advanced Materials”, Vol. 14, No. 2, 2002, pp. 99-117).